Margaret McPoyle has sparked a criminal investigation after complaining to Los Angeles police about an alleged online stalker.

The "Always Sunny in Philadelphia" star claims she was sent a string of degrading messages and vulgar images via the internet.

McPoyle also alleges she revealed several pictures via email spelling out the word 'c**t' in blood with a moving finger and has asked cops to investigate who is sending the messages.

Officers obtained a search warrant to investigate the anonymous online pest, tracing the messages back to a account by the name of 'dirtythesy' and have retrieved the user's email and IP addresses.

According to documents, obtained by, police now plan to launch a criminal investigation.